MPs, including some in Mays own party, have expressed anxiety about Trumps stance on a range of issues, including protectionism and torture. Global trade experts have warned that Britain may gain little from a bilateral trade deal with Washington.

But the prime minister will deliver a warm message about the two countries working closely together when she addresses senior Republicans at the partys annual retreat in Philadelphia on Thursday, before she meets Trump in the White House for face-to-face talks on Friday.

May will tell Republicans: The United Kingdom is by instinct and history a great, global nation that recognises its responsibilities to the world. And as we end our membership of the European Union as the British people voted with determination and quiet resolve to do last year we have the opportunity to reassert our belief in a confident, sovereign and global Britain, ready to build relationships with old friends and new allies alike.

So as we rediscover our confidence together as you renew your nation just as we renew ours we have the opportunity, indeed the responsibility, to renew the special relationship for this new age. We have the opportunity to lead, together, again.

Mays arrival comes as Trump signs off a volley of executive orders in a very public show of swiftly undoing the work of the Obama administration and beginning to honour pledges made on the campaign trail.

On Wednesday, Trump signed two executive orders to boost border security and crack down on immigrants living in the US illegally. On Tuesday, he angered Native Americans and climate change activists by signing executive orders to allow construction of the Dakota Access and Keystone XL oil pipelines. And on Monday, he reinstated the global gag rule, which bans aid funding for groups that offer abortions or abortion advocacy even if they use their own funds to do so.

Downing Street knows that many British voters are sceptical about Trump and his populist policies, some of which he has already taken steps to put into action. Thousands of people joined Womens Marches in cities across Britain last weekend to protest against his stance on womens rights.

But May has judged there is more to be gained by striking up what Downing Street sources called a grown up relationship with the new president than by remaining aloof.

Jeremy Corbyn, the Labour leader, accused the prime minister of threatening European partners while offering a blank cheque to President Trump, while the SNPs Angus Robertson pressed her on whether she was willing to downgrade Britains food standards to win a trade deal.

Andrew Tyrie, a senior Tory MP, also underlined the degree of concern in Mays party about Trump. At prime ministers questions, he said: President Trump has repeatedly said he will bring back torture as an instrument of policy. When she sees him on Friday, will the prime minister make it clear that in no circumstances will she permit Britain to be dragged into facilitating that torture, as we were after 11 September?

But trade experts are sceptical that a deal can be negotiated quickly and warn that the US may take advantage of its superior bargaining position as a much larger economy to force open Britains markets to US firms.

Adam Posen, a former member of the Bank of Englands monetary policy committee who is now president of the Peterson Institute of International Economics in Washington, said: It would require an enormous, transformative relationship with the US to make up for the decline in trade with the EU.

For 70 years, since the second world war, the US, beyond very narrow intelligence-sharing, has always treated the UK as subservient, or wanted it to be subservient.

He added: Theres a lot of reasons to think there will be very small upsides; I can say with very great confidence any gains made from such [a deal] will be a small fraction of what theyll lose.

Namali Mackay, trade adviser at manufacturers group EEF, said while there might be opportunities for British firms from a bilateral deal, average tariffs between the US and the EU were already low, at an average of 2%. She said the most likely blueprint for a future agreement would be the highly controversial TTIP agreement between the US and the EU.